1. Field of the Invention
The present invention relates to a disk drive which is intended for being equipped in a notebook computer, a desktop computer, CD-Player or DVD-Player and which reproduces CDs and DVDs, and particularly, to an antivibration device for such a disk drive which dampens vibration and noise among components of the disk drive.
2. Description of the Background Art
Recently, the speed of optical disk drives such as a CD-ROM DRIVE and DVD-ROM DRIVE is becoming much improved as 16xc3x97, 24xc3x97 and further 48xc3x97 speed, and due to this speed-up of the optical disk drive, there occurs a serious problem of vibration in case of driving a disk.
Particularly, in case of high-speed driving of a disk with an inclined center of gravity, the force of internal vibrations generated during a rotational cycle of a disk increases in proportion to the rotational speed of the disk, and in a disk drive mounted in a portable information processing apparatus and the like, this internal vibration is transmitted to a user""s hands or the vibration generates noise thus causes user""s displeasure or may decrease a reading capacity of information written on a disk. Also, in a DVD which is a high-density disk, the track pitch is half of that of a compact disk and accordingly, the reproducing capability of a disk is significantly decreased by such vibration.
To prevent vibration in such drives, a vibration damping member is installed between a base having a motor which generates such vibration and a main base for supporting the base.
FIG. 1A is a perspective view showing a vibration damper for a disk drive in accordance with the conventional art and FIG. 1B is a cross sectional view showing a main portion of a disk drive in which the vibration damper shown in FIG. 1A is used.
With reference to FIG. 1B, a tray unit 3 which moves for receiving a disk is installed in the disk drive, and a cover 1 is installed under the tray unit 3.
On the tray unit 3, a plurality of internally threaded bosses 3a are formed, and the cover 1 is fixed on the tray unit 3 by screws 5 which are threaded into the bosses 3a. 
Between the cover 1 and the tray unit 3, a pick-up unit (not shown) is positioned for recording a signal on a recording surface or reproducing the recorded signal.
Particularly, the pick-up base 9 for supporting the pick-up unit (not shown) is supported between the cover 1 and the tray unit 3 by vibration dampers 7 (only one of which is shown) so as to attenuate vibration and impact transmitted from external portions of the drive. A spindle motor (not shown) for rotating a disk is installed in the pick-up base 9.
With reference to FIGS. 1A and 1B, each of the vibration dampers 7 is formed in a cylindrical form of rubber material, with a hole 7a therethrough inserted onto the bosses 3a of the tray unit 3.
Also, an insertion groove 7d is formed in the circumferential surface of the vibration damper 7 so that the pick-up base 9 can be inserted thereinto.
In the vibration dampers 7, the whole inner surface of the hole 7a is contacted with the outer surface of the bosses 3a and the upper and lower surfaces 7b and 7c respectively are contacted with the cover 1 and the tray unit 3.
Therefore, the vibration damper 7 decreases vibration and impact transmitted between the pick-up base 9 and the cover 1 and the tray unit 3 in case of operating the drive.
However, the conventional vibration damper 7 for a disk drive has a disadvantage in that vibration damping characteristic thereof is reduced due to heat generated in a portable information processing apparatus and transmitted to the disk drive, since the upper and lower surfaces 7b and 7c support the pick-up base 9 in the condition that the surfaces are respectively adhered to the cover 1 and the tray unit 3 and accordingly the vibration damping characteristic is weakened since the vibration damper 7 can become softened and become stuck to the surfaces 7b and 7c when the interior environment of the disk drive is under a high temperature due to generation of heat in the electronic circuit elements installed in the disk drive.
Namely, since the vibration dampers 7 are made of a rubber material and is repeately subjected to cycles of high-temperature and low-temperature, their vibration damping capacity is declines. Particularly, because the upper and lower surfaces 7b and 7c are respectively contacted with the cover 1 and the tray unit 3, accordingly, the amount of vibration amount transmitted to the cover 1 and the tray unit 3 through the vibration damper 7 relatively increases.
The vibration damping characteristics of the vibration damper 7 can be described with reference to FIG. 2 wherein the condition where vibrations generated when the disk drive is operating are transmitted to the outside is deemed as transmission rate 1 in a transmission curve. If the transmission rate is greater than 1, vibrations are amplified and transmitted to the outside and if the transmission rate is less than 1, vibrations are attenuated and transmitted to the outside.
The resonant frequency of the vibrations generated in the disk drive is 150 Hz and occurs at point B of the transmission curve in FIG. 2 exhibiting a maximum vibration transmission rate.
In case the disk drive is operated at 24xc3x97 speed (24xc3x97 the nominal xe2x80x9csinglexe2x80x9d speed), the disk mounted in the drive rotates at 4,800xcx9c5,000 rpm and the frequency of vibration is 85xcx9c90 Hz. Point A in FIG. 2 represents the transmission rate in the case where the disk drive operates at 24xc3x97 speed. The transmission rate according to the transmission curve is more than 1 and the vibration of the pick-up base 9 is amplified and transmitted to the outside due to a decrease in the vibration damping effect of the vibration damper 7.
To solve the problem, a washer or powder is used between the vibration damper 7, cover land the tray unit 3 to prevent the vibration damper from becoming softened and stuck under the conditions of high temperature and humidity. However, they increase the number of the components and complexity of the drive.
Particularly, since the conventional vibration damper 7 is installed in the condition that the upper and lower surfaces 7b and 7c are contacted with the cover 1 and tray unit 3 and the hole 7a is completely contacted with the bosses 3a to afford the vibration damping function, the resonant frequency is increased and accordingly, the damper can not attenuate vibrations sufficiently and thus transmits vibrations directly. Therefore, a user receives the vibration generated when operating the disk drive as it is.
A ball balance mechanism has conventionally also been applied to a turntable and the like in an attempt to solve the vibration problem. However, if a ball balance mechanism is used, the number of components increases thus increasing the cost.
Therefore, an object of the present invention is to provide an antivibration device for disk drive which can minimize vibration transmitted to the outside by attenuating vibration generated in the disk drive efficiently, to solve the above problem.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an antivibration device for a disk drive which has a pick-up unit in which a pick-up is mounted to reproduce information recorded in a disk or record information in the disk with a pick-up unit supporting unit wherein an upper supporting member and a lower supporting member are positioned above and below the pick-up unit and the upper supporting member and lower supporting member are fixed mutually in a separated position having a certain space therebetween by a fixing member, the antivibratiion device comprising a vibration damper for supporting the pick-up unit between the upper supporting member and the lower supporting member of the pick-up unit supporting means, where the vibration damping means has the pick-up unit fixed on an outer circumferential surface thereof and a plurality of contact protrusions are formed on at least one surface among the upper surface and the lower surface thereof contacted with the pick-up unit supporting means.
A hole is formed penetrating the upper and lower surface of the vibration damping means so that the vibration damping means may be inserted over the outer end of the fixing member, and inside the hole, a plurality of contact ribs are formed to be contacted with the fixing member.
In accordance with the invention there is provided an antivibration device for a disk drive which includes a pick-up unit in which a pick-up is mounted to reproduce information recorded in a disk or record information in the disk, and a pick-up unit supporting means wherein an upper supporting member and a lower supporting member are positioned above and below of the pick-up unit and the upper supporting member and lower supporting member are fixed mutually in a separated position with a certain space therebetween by a fixing member, the antivibration damping means comprising a vibration damping means for supporting the pick-up unit between the upper supporting member and the lower supporting member of the pick-up unit supporting means, wherein the vibration damping means has means for fixing the pick-up unit fixed on an outer circumferential surface thereof, a hole is formed penetrating upper and lower portions of the vibration damping means so that the vibration damping means can be inserted onto an outer end of the fixing member, and a plurality of contact ribs are formed inside the hole to be contacted with the fixing member.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.